Means for damping oscillations



' BgvoN scHLlPPE File@ Sept. 5, 1936 BEANS FOR DAIPING OSCILLTIONS Marchv26, 1940.

all/111;);il 4s iented Mar. 26, 1946 STATES wir OFFHCE 2,195,041l MEANSFon DAMPING oscmm'rIoNs Application september-5, 1936, sei-iai No.99,677 In Germany September 23, 1935 10 Claims.

My invention relates to means for damping oscillations arising inmachinery, in buildings or the like. It is an object of my invention toprovide means of the kind aforesaid which are simpler in constructionand use and more efcient than other devices hitherto designed for. thesame purpose land which offer other advantages of their own Whichwill bedescribed farther below.

Many kinds of oscillation damping devices have been suggested, in mostof which oscillatory movements of parts of a building, of a machine orthe like are damped by the transformation of a material part of theenergy, which incites or generates the oscillation, into externalfrictional energy, which is consumed by two friction members shiftingrelative to each other during the oscillationk and one of which isconnected with the oscillating part. In some of the prior devices theinner friction of a liquid has been resorted to for the damping ofoscillations, for instance by forcing this liquid through narrowpassages. While damping devices of the kinds aforesaid frequentlyVrender useful services, most of them present a comparatively involvedand heavy construction. There have further been suggested dampingdevices in which oscillations are damped by the consumption of energy bya damping member set to oscillate in resonance with the kind involve thedrawback of becoming operative only at the predetermined oscillationfrequency to which the damping member is tuned.

The damping device according to the present invention is of very simpledesign and extremely light in weight. It offers the further advantage ofbeing iit to be mounted in place also subsequently on the parts of abuilding, a machine or the like endangered by oscillations.

The invention is based on the conception that vthe generation ofdangerous-oscillatory conditions can be avoided by mounting near thatpoint of the oscillating part, at which the maximum of the oscillationsoccurs, a yielding (elastic) body possessing a considerable innerfriction and which is freely movable, at least within certain limits.Free mobility of this body is limited either by stops, casings, springsor links or by the circumstance that the yielding body embraces theoscillating part. Whenever oscillations arise. the` damping body ispermanently imparted shocks acting in the opposite direction and isthereby shaken and set oscillating, whereby it is subjected to a varyingelastic deformation. 'I'he energy resulting from such deformation isoscillation to be damped. Devices of this latterv (Cl. 18S- 193) notrecovered in full, but is partly converted into heat. This consumptionof energy reduces the amplitude of the oscillations of the oscillatingpart to the extent that dangerous oscillatory conditions are notattained.

'I'he damping body may consist of several parts held together in anelastic manner and relatively displaceable under friction. I may forinstance employ a hollow body with elastic'walls filled with a granularor highly viscous material such 4as for instance sand, or a siruplikemass. I have, however, found it preferable to form the damping body as awhole from an elastic material possessing a high inner friction, such asfor instance rubber, leather or the like. A particularly suitable devicewhich is quite especially adapted for damping transversal oscillationsof comparatively long and thin parts, has the form of a ring of amaterial of the kind aforesaid which possesses high inner friction, theinner diameter of this ring being somewhat larger than the diameter ofthe part, the oscillations of which shall be damped. This ring ismounted on and embraces the part.

In4 the drawing aixed to this specication and forming part thereofdamping devices embodying my invention are illustrated diagrammaticallyby Way of example. In the drawing Fig. 1 is a vertical axial section ofa damping device consisting of several coacting parts.

Fig. 2 is a similar view of a damping device comprising a damping bodymade of a material possessing considerable inner friction.

Fig. 3 is an elevation, partly in section, of another device in which adamping body of similar material is guided by a link, and

Fig. 4 illustrates the application of Asuch a device to verticallyextending parts to be protected.

Fig. 5 illustrates a further modification of the same device, in which aspring is provided to return the damping member into/its position ofrest.

' Fig. 6 is an elevation, partly inl axial section, which comprises anannular damping member formed of a material of high inner friction.

Fig. '7 is a vertical axial view of a damping device in which thedamping body is a thin- Walled sheet metal box rvfilled with sand.

Referring to the drawing and rst to Fig. 1, I is a conventional showingof a structural member subject to oscillations and 2 is a casing fixedto this part. 3 is/the damping body enclosed in this casing, the bodyconsisting of two relatively slidable sleeves 4 and 5, which areconnected by 55 .ring I.

a firmly clamped tension and compression spring 6. 1 is the cylindricalfrictional surface formed on the part 4, and 8 is an. annular springfirmly embracing the part l and seated in an ann'ular depression I8formed in the part 5.

0n the shocks generated by the oscillatory movements of the part I beingtransmitted to the damping body, the part 5 will move away from the partI. The part l, being displaceable relatively to the part 5, will not beimparted at once the complete velocity of the part 5, but will partlyslide in the same, spring I being simultaneously compressed. The morevigorous the oscillations of part I, which are transmitted to the part5, the deeper the part I will first slide into the part 5 and the morespring 5 will be compressed. The spring will tend to expand again and totransmit the energy stored in it the part I. A considerable portion ofthis energy is transformed into heat by the friction generated betweenthe surface `1 and the elastic This amount of energy .is withdrawn fromthe oscillatory energy of the part I, the amplitude of the oscillations-of which is thus reduced. The same events occur on the damping body 3striking the top ofthe casing 2, so that the part 4 is imparted a shockfrom above, and the same series of movements and energy transmissionswill be gonethrough anew each time the body 3 is imparted a shock frombelow or from above. Due to the relatively slidable sleeves l and 5, themovements of the damping body 3 can never adopt the frequency of' theoscillations of the'part I, so that part of the energy of motion iscontinuously transformed into frictional heat.

While the inner friction of the damping body shown in Fig. 1 resultsfrom the friction of its parts 4, 5 and I, respectively, the innerfriction of the damping bodies, illustrated in Figs. 2-6 is that of thematerial of which these bodies consist. In the modification illustratedin Fig. 2 a casing 22 is xed to the part I, which encloses a dampingbody 23 having the form'of a freely movable rubber ball. The action ofthe ball in the casing will readily be understood from the descriptiongiven with reference to Fig. l.

' In the device shown in Fig. 3 a plate I is fixed to the oscillatingpart I. To this plate isn pivoted at I0 a link II, on the free end ofwhich is mounted a rubber or leather ball Il, which forms the dampingbody, the movements of which are limited by the check I2.

Fig. 4 illustrates the action of this damping device in connection withavertically extending part I which is assumed to oscillate in horizontaldirection.

Fig. 5 shows a similar damping device mounted on the bottom surface ofthe part I to be protected. Here the link BI carrying the rubber ball 34is held applied to the plate 9 by a coil sprng 35 which serves to returnthe damping body to its original position after it has received a shock.

In the modification illustrated in Fig. 6 'the part 4I to be protectedhas the form of a tube, the horizontal oscillations of .which areintended to be' damped. A casing 42 is held on the tube by means ofclamping rings I4. The casing encloses a ring made of a material ofconsiderable inner friction, such as rubber, leatherv or the like, theinner diameter of which is so much larger than the outer diameter of thetube 4I, that the ring 43 moves freely on the tube;

Obviously, when the tube is set oscillating transversally to itslongitudinal axis, the rubber ring in contact with the tube will be setoscillating also, always returning into contact with the tube at variousplaces and by its impact damping the oscillations of the latter.

In the modication showx in Pig. 7, the thinwalled sheet metal casing 52lled with sand 53 is mounted by means of the brackets 5l on the part Iwhich is assumed to be endangered by vertical oscillations. The walls ofthe casing 52 and particularly the bottom 54 are elastic so as totransmit oscillations of the part I to the sand 53 which acts as adamping means, since frictional heat is developed by the inner frictionproduced by the relative movements of the individual grains. The energythus transformed into heat is withdrawn from the oscillation energy ofthe part I.

The term at least indirect contact" as used in the appended claims isintended to refer to either direct contact, or else to contact throughan intermediate part such as the bottom parts of the casings in Figs. 1and 2, or the bottom parts of the stroke limiting means in Figs. 3, 4and 5. Evidently, for the purposes oi' the invention all structuralarrangements have in common that the freely movable damping body isnormally in physical contact, whether direct or indirect, with theoscillating member, while being physically removed from such member uponthe occurrence of oscillation therein.

I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described for obviousmodifications will o'ccur to a person skilled in the art.

I claim:

1. A -damping device for damping oscillations of a'structural member andthe like, comprising in combination a freely movable damping bodyarranged on said structural member so as to be normally in at leastindirect contact therewith while oscillating within predetermined limitsupon the'occurrence of oscillations in the structural member, saiddamping body being elastic so as to be deformed during oscillation whilebeing adapted to oppose to such deformation' a resistance suiilcing todamp said oscillations.

2. A damping device for damping oscillations of a structural member andthe like, comprising in combination stroke limiting means mounted onsaid structural member and a freely movable damping body arranged insaid stroke limiting means so as to normally be in at least indirectcontact with said structural member while oscillating within the limitsdefined by said stroke limiting means upon the occurrence ofoscillations in the structural member, said damp ing body being elasticso as to de deformed during oscillation while being adapted to oppose tosuch defamation a resistance sutlicing to damp said oscillations.

3. A device for damping oscillations of a structural member and thelike, comprising in combination a casing arranged upon the memberssubject to oscillations, and a freely movable elastic damping bodywithin the casing, said elastic body being deformed during oscillationby at least indirect contact with such structural member, said bodyopposing to such deformation a resistance which acts to dampen saidoscillations in the structural member.

4. A device for damping oscillations of structural members and the likecomprising in combination a freely movable damping body suposcillatingwithin predetermined limits in re.

sponse to oscillations set up in the structural member, said dampingbody being elastic and being deformed by at least indirect contact withsuch structural member during oscillation, said body opposing to suchdeformation a resistance which acts to dampen said oscillations in thevstructural member.

5. A device lfor damping oscillations of a structural member and thelike comprising an elastic damping body possessing considerable innerfriction arranged to normally rest in at least indirect contact withsaid member, and means positioned by said member forl conning themovement .of said body within specic limits whereby on oscillation ofthe member the body is free to bounce repeatedly betweenA said memberand said coni-ming means to thereby absorb the energy from saidoscillations.

6. A device for damping oscillations of a part of a building, machine orthe-like, comprising a freely movable elastic damping body possessing aconsiderable inner friction, said body being in at least indirectcontact with the oscillating part.

7. The damping device of claim 6 wherein the damping body consists ofrubber.

8. 'I'he damping device of claim 6 wherein the damping body comprises aring arranged to surround the oscillating part and provide a clearancetherebetween.

9. A device "for damping oscillations of a part of a building, machineor the like, comprising' a damping body in two parts arranged formovement relative to each other, one of said parts being normally in atleast indirect contact with the part to be damped, said body beingfreely movable as a unit, means associated with the parts of saiddamping body operable to frictionally resist relative movement betweenthe two, and yieldable means tending to retain said damping body partsin predetermined relative position.

10. AA device for damping oscillations of a part of a building, machineor the like, comprising two sleeves arranged for relative telescoplngmovement, resilient means adapted to resist relative movement of the twoparts, means for creating inner friction between the telescoped surfacesof the two parts'on relative-movement thereof, said device beingarranged with reference lto the oscillating part in such manner as tonormally lie in s at least indirect contact therewith.

BoRIs 'von soma.

